Quality of life measures for food allergy

Food allergy has become an emerging health problem in Western societies. Although food allergy is characterized by a relatively low mortality and an almost continual absence of physical symptoms, food allergic patients are continually confronted with the possibility of potentially severe reactions and the necessity of dietary vigilance. Health-related quality of life (HRQL) may be the only meaningful outcome measure available for food allergy measuring this continuous burden. HRQL may be measured with generic or disease-specific instruments. Generic instruments may be relatively unresponsive to differences or changes in health status, whereas disease-specific instruments are generally more sensitive for relatively subtle problems related to a particular illness. Recently, a number of disease-specific questionnaires have become available to measure the HRQL of food allergic patients. An important area for further research is the interpretation of the outcome of HRQL measures. In this respect, the minimal clinically important difference (MCID) is of special interest. In combination with the numbers needed to treat (NNT), this may give an ultimate insight into the clinical relevance of an intervention. Since there is still no cure for food allergy, the only available treatment is strict avoidance of the culprit food and provision of emergency treatment. The double-blind placebo-controlled food challenge (DBPCFC) is considered to be the gold standard for diagnosing food allergy. A number of studies have investigated the perceptions of parents whose children underwent a DBPCFC. In contrast to the parental perception, there is much currently still unknown about the effects of undergoing a DBPCFC in the perceptions of patients. In addition to the research on MCID and NNT of food allergy HRQL questionnaires, further research should focus on deriving quality-adjusted life years (QALYs) from food allergy HRQL questionnaires and the application of food allergy HRQL questionnaires at the individual patient level in clinical practice.     

Genetic and environmental risk factors for the development of food allergy

PURPOSE OF REVIEW: To review recent clinical and experimental studies of genetic and environmental risk factors for the development of food allergy. RECENT FINDINGS: It may be true, although it is yet to be shown, that food allergies in early childhood are becoming more common and that the causes are the same as for later-developing respiratory allergies. The mother not only transfers 50% of her genes to her baby, but she is also the exclusive environment during gestation and continues to be a major environmental factor while breast-feeding her infant. Non-genetic maternal influences increasing the likelihood of food allergy include Caesarian section and high maternal age. Allergy to sesame seems to be increasing in children. This is possibly a consequence of increased use in processed foods. The search for dietary risk factors is not limited to allergenic foods, but may include other nutrients, for example excessive intake of vitamins. Two meta-analyses have seriously questioned the use of special infant formulas for allergy prevention. Novel prevention strategies, such as probiotic bacteria, have yet to be documented further. SUMMARY: The causes of food allergy are still unknown and no particular genes associated particularly with food allergy have been identified, although there is a strong association in general between genetic susceptibility to food allergy and that to IgE-mediated allergy. There are still no measures for general recommendation in order to prevent food allergy and no genes have been linked conclusively to disease. Further research concentrating on food allergy is obviously needed.     

The impact of childhood food allergy on quality of life.

BACKGROUND: Food allergy affects >6% of children, but the impact of this disease on health-related quality of life has not been well studied. METHODS: Parental perceptions of physical and psychosocial functioning were measured with the Children's Health Questionnaire (CHQ-PF50). This tool and an additional allergy-related questionnaire were sent to 400 members of the Food Allergy and Anaphylaxis Network with children aged 5 to 18, an age group on which the tool has been validated. RESULTS: Surveys were completed by 253 parents (63%). The mean age of the food-allergic children was 10.8 years (range, 5 to 18 yrs); 59% were male. Sixty-eight percent were allergic to one or two foods, the remainder to more than two foods. Concomitant chronic atopic diseases included: asthma with atopic dermatitis (33%), atopic dermatitis alone (13%), asthma alone (33%), and 21% had neither asthma nor atopic dermatitis. In comparison to previously established norms, the families scored significantly lower (more than 10 scale score points lower and P < 0.0001) for general health perception (GH), emotional impact on the parent (PE), and limitation on family activities (FA). Associated atopic disease, influenced primarily by those with both asthma and atopic dermatitis, accounted for a significant reduction in the GH scale (analysis of variance, P = 0.0001), but not for measures of PE and FA. Within the study group, food-allergic individuals with several (more than two) food allergies had significantly lower (P < 0.05) scores for 7 of 12 scales compared with individuals with few (one or two) food allergies. However, those with one or two food allergies scored significantly lower (P < 0.0001) than established norms on scales for GH, PE, and FA. CONCLUSIONS: Childhood food allergy has a significant impact on GH, PE, and FA. Factors that influence reductions in these scales include associated atopic disease and the number of foods being avoided.     

Important risk factors for the development of food allergy and potential options for prevention

Introduction: Food allergy currently affects up to 10% of infants. Identification and implementation of effective food allergy prevention strategies is thus imperative.

Areas covered: We focus on five food allergy risk factors/prevention strategies which have been or are currently being tested in randomized controlled trials: (1) timely introduction of allergenic foods into the infant diet; (2) maternal diet and consumption of allergenic foods during pregnancy and breastfeeding; (3) infant skin barrier and the role of moisturizers in early life; (4) infant Vitamin D levels and the role of Vitamin D supplementation; and (5) microbial exposure in early life.

Expert commentary: Earlier introduction of allergenic foods, particularly peanut, in the infant diet has been shown to reduce food allergy. Novel intervention strategies, including infant vitamin D supplementation, maternal diet modifications, and moisturizing infants to improve skin barrier, are currently being tested in large-scale clinical trials. As results of these trials become available, we hope strategies that are both efficacious and cost-effective will be revealed and their implementation in the population, along with the timely introduction of allergenic foods, will reduce the burden of food allergy in future generations.     

The impact of oral food challenge tests on food allergy health‐related quality of life

Food allergy health‐related quality of life (FAQOL) has been shown to improve after food challenge, but it is unknown whether this improvement is attributed to the procedure itself. Using the Food Allergy Quality of Life Questionnaire–Parent Form, we assessed FAQOL changes over time for children who underwent food challenges in the only paediatric allergy clinic in Ireland. Of 54 children who had a food challenge between September 2012 and February 2013, 25 were positive (allergic) and 29 were negative (nonallergic). FAQOL improved significantly from 2 months prechallenge to 2 months postchallenge for both groups, but began to decrease at 6 months postchallenge in allergic patients. Our findings confirm the positive therapeutic effect of the food challenge on FAQOL; however, the effect appears to wane between 2 and 6 months postchallenge in those confirmed food‐allergic, highlighting the importance of regular contact with families of food‐allergic children after the food challenge.     

Mechanisms of food allergy

The prevalence of food allergy continues to rise, particularly in 'westernized' societies; it has been linked to the 'hygiene hypothesis' and the increased diversity of food consumption worldwide. The pathogenic mechanisms and Th1/Th2 paradigm are being closely examined with respect to the occurrence of inflammatory and injury/repair responses at different mucosal sites. Genetically modified plants as potential food sources and allergenicity are current topics of controversy.     

Epidemiology of food allergy

Adverse reactions to foods can occur for a variety of reasons, but a food allergy is caused by a specific immune response. Challenges to determine the prevalence of food allergy include misclassification, biased participation, lack of simple diagnostic tests, rapid evolution of disease, large numbers of potential triggers, and varied clinical phenotypes. Nonetheless, it is clear that this is a common disorder, with studies suggesting a cumulative prevalence of 3% to 6%, representing a significant impact on quality of life and costs. The inclusion of mild reactions to fruits and vegetables could result in calculation of prevalence exceeding 10% in some regions. There are data from numerous studies to suggest an increase in prevalence, but methodologic concerns warrant caution. Prevalence varies by age, geographic location, and possibly race/ethnicity. Many childhood food allergies resolve. Population-based epidemiologic studies have generated numerous novel theories regarding risks, including modifiable factors such as components of the maternal and infant diet, obesity, and the timing of food introduction. Recent and ongoing studies provide insights on risk factors, prevalence, and natural course that may inform clinical trials to improve diagnosis, prevention, and treatment.     

Determinants of food allergy

Food allergy is an emerging epidemic in the United States and the Western world. The determination of factors that make certain foods allergenic is still not clearly understood. Only a tiny fraction of thousands of proteins and other molecules is responsible for inducing food allergy. In this review, the authors present 3 examples of food allergies with disparate clinical presentations: peanut, soy, and mammalian meat. The potential relationships between allergen structure and function, emphasizing the importance of cross-reactive determinants, immunoglobulin E antibodies to the oligosaccharides, and the immune responses induced in humans are discussed.